This study will evaluate changes in the physiology of the urinary tract following bacterial infection. We will utilize I131 hippuran scintiphoto studies, excretory urograms and cystograms. In addition, in vivo studies of ureteral physiology will be done. To correlate with changes in physiology, studies of humoral and cellular immunity will be done. In some monkeys, immunodepression will be produced by treatment with azathioprine and cyclophosphamide prior to infection. Possible coaction of bacterial variants and viral renal infections will be controlled by study of them during bacterial renal infection with and without immunodepression. BIBLIOGRAPHIC REFERENCES: Roberts, J.A., and Domingue, G.: Experimental pyelonephritis in the monkey. II. The prognostic value of radionuclide evaluation of the urinary tract. Invest. Urol. 12:374-380, 1975. Roberts, J.A.: Experimental pyelonephritis in the monkey. III. Pathophysiology of ureteral malfunction induced by bacteria. Invest. Urol. 13:117-120, 1975.